Refrigerant vapor compressor



y 8, 1968 c. R. KILG RE 3,385,513

REFRIGERANT VAPOR COMPRESSOR Filed April 11, 1966 5 Sheets-Sheet l BY al h ATTORNEYS y 8, 1968 c. R. KlLGORE 3,385,513

REFRIGERANT VAPOR COMPRESSOR Filed April 11, 1966 5 Sheets-Sheet 8 wai M WA WATTORNEYS y 1968 c. R. KILGORE 3,385,513.

REFRIGERANT VAPOR COMPRESSOR Filed April 11, 1966 5 Sheets-Sheet 5 l N VEN TOR.

Cizaz lesfii zgare BY 9%IM/ ATTORNEYS y 3, 1968 c. R. KILGORE 3,385,513

REFR IGERANT VAPOR COMPRES SOR Filed April 11, 1966 5 Sheets-Sheet 4 INVENTOR. kaz leszEZ gore By Zak WATTORNEH y 28, 1968 c. R. KILGORE 3,385,513

REFRIGERANT VAPOR COMPRESSOR Filed April 11, 1966 5 Sheets-Sheet 5 I N VEN TOR.

Lax @AflATTORA/EYS United States Patent Oflice 3,3355% Patented May 28, 1968 3,385,513 REFRIGERANT VAPOR COMPRESSUR Charles R. Kilgore, Willowiclr, Ohio, assignor to TRW Inc, Cleveland, Uhio, a corporation of Ohio Filed Apr. 11, 1966, Ser. No. 541,836 Claims. (Cl. 230152) This invention relates to an improvement in a refrigerant vapor compressor characterized by a double row of circumferentially spaced discharge ports controlled by reed valve means so that the ports open in unison and close in pairs in discharging to a pressure reservoir. A swivel tube dips into the lower part of the pressure reservoir and carries liquid lubricant to the inside of the pump, regardless of the pump orientation in left, right or vertical mounting positions, and special scavenging grooves in the faces of the bearing plates minimize leakage into the suction side of the compressor. And, in accordance with the present invention a demister element is provided between the discharge ports and the reservoirs for materially aiding separation of the oil lubricant from the refrigerant.

The invention has the object and advantage of improv ing overall refrigeration system efficiency by retaining lubricant in the compressor.

On the drawings:

FIG. 1 is a reduced scale overall outside view of the rotary vane vapor compressor of the present invention adapted for external drive;

FIG. 2 is a longitudinal crosssectional view of the compressor of FIG. 1;

FIG. 3 is an axial cross-sectional view taken on line III-III of FIG. 2;

FIG. 4 is a fragmentary cross-sectional view with parts broken away to illustrate additional details of the reed valve means and discharge port arrangement and is taken substantially on line IV-IV of FIG. 3;

FIG. 5 is an inside view of the front bearing plate taken on line V-V of FIG. 2;

FIG. 6 is a fragmentary cross sectional view taken on line VIV I of FIG. 3;

FIG. 7 is a fragmentary cross-sectional view taken on line VlL-VII of FIG. 8; and

FIG. 8 is an axial crosssectional view taken on line VIII-VIII of FIG. 2.

The rotary vane vapor compressor of the present invention is shown generally at 10 and comprises a casing 11 connected by means of a plurality of lug bolts 12 to a front bearing plate 13, the lug bolts 12 cooperating with suitable washers 14 and nuts 16, thereby to form an integral housing assembly. The casing 11 is generally cup-shaped in configuration and has an end wall 17. A recessed lip 18 overlies a correspondingly recessed portion 19 formed in the front bearing plate 13 and in which is seated an O ring sealing member 20 (FIG. 2).

The bearing plate 13 is characterized by the formation thereon of a boss 21. The boss 21 receives suitable coupling means shown generally at 23 (FIG. 5) for connection thereto of an inlet service valve.

The casing 11 has a boss 22 which also has suitable coupling means 26 connected thereto by means of which a discharge service valve may be connected to the compressor.

As is most clearly shown in FIGS. 1 and 5, the front bearing plate 13 has plural mounting pads formed thereon disposed to afford right, left and vertical mounting. The separate mounting pads are arranged in different planes on plural sides so that a first set of mounting pads is shown at 28, 28, while a second set of mounting pads is shown at 29, 29 and a third set of mounting pads is shown at 30, 30.

A casing cylinder is shown at 31 (FIG. 3) and has formed therein a bore 32 in which is received a rotor 33. The casing cylinder 31 has a plurality of circumferentially spaced slots 34 which engage fastening bolts 36 used to secure a rear bearing plate 37 in assembly with the front bearing plate 13.

The rear bearing plate 37 has an axially projecting boss 38 forming a bearing housing in which is received a needle bearing assembly 39. A rotatable shaft 41 has a bearing portion 42 journaled in the needle hearing assembly 39 and projects through the bore 32 of the casing cylinder 31 and through an opening 43 formed in the front bearing plate 13. The opening 43 is counterbored at 44 from the outside of the front bearing plate 13 to receive a double roll ball bearing assembly shown generally at 46, the inner race of which engages against a bearing portion 47 on the shaft 41. In constructing, the assembly 46 is inserted from the front of the plate 13 and is held therein by restraining means 46. Installing the assembly 26 through the front or outside surface of the bearing plate 13 permits use of a radial inward lip 13a extension to the inner surface of the front bearing plate 13. This increases the length of the leakage path across the annulus defined by the inside surface of the front bearing plate and the front inside surface of the rotor 33. The shaft 41 is journaled in the front and rear bearing plates 13 and 37. A rotary seal assembly 48 is provided to effect a shaft seal with the shaft 41 and a seal end plate 49. The plate 49 is attached to the end of the front bearing plate 13 by a plurality of bolts 50. A coupling portion 51 on the shaft 41 projects outwardly for connection to a suitable source of power for the compressors.

Between the bearing portions 42 and 47, the shaft 41 as a splined portion 52 and disposed intermediate section 43 and reduced diameter section 54. The splined section 52 is co-rotatable and connected with a correspondingly splined internal bore 56 formed in the rotor 33, thereby permitting the rotor to move axially in a selfcentering action between the front and rear bearing plates 13 and 37, while insuring a good rotatable drive connection between the rotor 33 and the shaft 41.

A snap-type retainer ring 46 is used to hold the ball bearing assembly 46 in place in the counterbore 44 of the front bearing plate 13.

As shown in FIG. 3, the rotor 33 is disposed within the bore 32 of the casing cylinder in eccentrically offset relation relative to the bore axis and a portion of the rotor 33 is in tangent seal contact with the casing cylinder as shown at 58.

The rotor 33 has formed in the peripheral surface thereof a plurality of circumferentially spaced vane slots each identified at 59, which slots are enlarged at their outer ends to form recesses 66. Received within each vane slot is a slidable vane 61 having a rounded outer end 62 which engages into the socket 63 of a vane shoe 64. A toe or leading end 66 of each shoe 64 is somewhat longer than the heel or trailing end 67 of each respective shoe 64, thereby permitting the shoe to develop a planing action with respect to the adjoining bore wall.

A pair of pins 68 extend between oppositely disposed vanes 61 and each pin 68 is surrounded by a coil spring 69 bottomed against an end wall 70 of a corresponding vane, in order to bias the vanes in outward direction. The ends of the pins 68, 68 are received in corresponding recesses 71, 71. The shaft 41 is provided with transverse passages 72 through which the pins 68, 68 and corresponding springs 69 extend. As shown in FIG. 6, the rotor is also formed with passages 73 for a similar purpose.

Referring now more particularly to FIGS. 3 and 5, it will be noted that the boss 21 has extending therethrough an inlet passage 76 which communicates with a kidneyshaped inlet recess 77 formed in a radial face 78 of the front bearing plate 13. The kidney-shaped inlet recess 77 is located adjacent the crescent-shaped working chamber 79 which extends around from the point of tangent contact 58 through an inlet side circumferentially towards an outlet side.

Fluid entering the compressor passes through the passage 76 and the recess 77 to fill the expanding inlet area between adjacent vanes 61 as they move through the working chamber 79.

On the discharge side of the compressor, the casing cylinder is particularly characterized by the formation of a first boss 80a adjacent the tangent contact area 58 and having formed thereon a flat valve-seating surface 81 (FIG. 4). A double row of openings extends from the working chamber 79 outwardly and intersects the valveseating surface 81 at opposite sides thereof, thereby forming two axially separated rows of circumferentially spaced discharge ports each indicated at 82.

A reed valve means is provided to form plural valves for independent regulation of the discharge ports 82 and in this regard, the valve means comprises a main body member 83 having a plurality of digital projections or reeds, each of which is shown at 84. Each reed 84 comprises a spring finger for overlying a corresponding port 82, thereby to engage the valve seating surface 81 and regulating the opening and closing of a corresponding opening or port 82.

A holddown and travel-limiter clamp is shown at 86 and is fastened to the boss by a pair of spaced fasteners 87, 87. The reed valve element 83 can be made of a suitable resilient material such as spring metal. Referring to FIG. 4, specifically, it will be noted that a recess groove 88 is located adjacent each row of openings or ports 82, thereby to insure venting of the underside of the individual reeds 84 and further insuring that the reeds 84 will seat against the valve seating surface 81 in register with a corresponding opening or port 82.

A second boss 80b is provided on the casing cylinder 31 to provide a second series of openings or ports extending circumferentially towards the inlet side of the compressor so that there is an upper set of valves and a lower set of valves. Since the construction is otherwise identical, like reference numerals have been applied to like parts.

Fluid discharged through the ports 82 is directed into a pressure reservoir 90 formed inside of the casing 11 and outside of the casing cylinder 31. It will be noted that the outer periphery 91 of the rear bearing plate 37 is continuous (FIG. 8), and serves to define a number of flow channels 90f of a curving slot configuration each of which is defined between adjacent circumferentially spaced boats 36 and lie about equal length and commonly centered are segments.

As shown in FIGS. 2 and 8, a swivel mounted lubricant pick-up tube is provided at 98. The tube 98 is positioned in FIGS. 2 and 8 as it would dwell with the compressor mounted in the vertical position. Thus, it will be noted that a radial end wall 100 formed in the housing 38 of the rear bearing plate 37 has an opening 101 formed therein through which extends a hub 106. The hub 106 is offset at 107 to retain the tube 98 in relatively rotatable assembly in the wall 100. A flange 108 is formed on the hub 106 in spaced relation to the offset portion 107 and overlies the wall 100. The tube 98 has a portion at 109 which extends within hub 106 and communicates therethrough to the bearing 39. The tube 98 depends gravitationally towards the lowermost portion of the pressure reservoir 90 opening at 110.

In operation, counterclockwise rotation of the rotor 33 and the attached vanes 61 and shoes 64, as viewed in the orientation of FIG. 3, causes pressure in the suction side of the compressor to be reduced. This, in turn, causes gaseous refrigerant and minute quantities of lubricant in mist form to flow into the suction passage 76 and pass through the suction kidney 77 to fill the cavity between vanes 61, 61. In FIG. 3, the vane at the bottom of the drawing is shown at the point where its leading edge has just cut off the working chamber 79 from the suction kidney 77. Thus, compression is about to commence in the corresponding portion of the working chamber between the bottom vane and the lower right vane.

The relative position of the rotor 33 and any particular vane 61 at the time the discharge reed valves 84 first operate depends upon the discharge pressure. At very low discharge pressures, nearly all of the reed valves 84 operate. At maximum pressure only the reed valves 84 between the uppermost vane and the point of tangent contact 58 would operate. Both sets of reed valves 84 in both of the bosses 80a and 8012 open upon start-up. This purges the space swept by the vanes 61 of lubricant and liquid refrigerant and promotes rapid pressure buildup.

The lowermost reed valves in the secondary valve set, i.e., that valve set farthest from the point of tangent contact 58, are located so that upon startup they will open shortly after suction kidney cutoff, thus preventing liquid lock.

It is contemplated that each of the openings or discharge ports 82 will be sized to have a diameter somewhat smaller than the circumferential width of a corresponding shoe 64. Such relationship accomplishes two objectives. First of all, compressed gas will not by-pass across the ports 82 from the leading to the trailing cavity as the shoe crosses the port openings 82. Secondly, the individual reed valves 84 are given time to close before each respective shoe 64 passes. If the shoe 64 were to pass a valve port 82 before the reed valve 84 for that port 82 closed, compressed refrigerant would flood through the valve port 82 into the trailing cavity. This would raise discharge temperatures and horsepower required to drive the compressor.

One advantage of the compressor is that rapid valve opening and closing is promoted by the low mass and short travel of the individual reed valves 84 and by venting the under surface of the reed valves 84 with the relief grooves 88, 88. Such grooves 88, 88 prevent the reed valves 84 from clinging to the casing cylinder 31 at any point other than the valve seating surfaces 81, 81. The grooves 88, 88 also assist in venting the discharged fluids from the valve area.

Another advantage of the compressor resides in the low level of valve noise which occurs because all of the valves, or a percentage of them, depending on the discharge pressure, open simultaneously but close in pairs. Further, the low valve mass and the short valve travel also promotes quiet operation.

It will be noted upon referring to FIG. 3, that the inner end of the last pair of discharge ports 82, 82 is located very near to the line of tangency 58. This is specifically arranged to minimize the volume of fluid which would otherwise become trapped between the line of tangency and the shoe 64 after the shoe 64 passes the last pair of discharge ports 82, 82. Accordingly, vane thumping is eliminated which might occur if the pressure is relieved by inward displacement of the vanes because of trapped fluid.

The valve arrangement of the present invention also affords greatly improved reduction in over-compression, thereby reducing drive torque, discharge temperature, vibration and leakage through the tangency clearance. It also reduces leakage through the annular clearances between the adjoining faces of the bearing plates 13 and 37 and the rotor 33. Fluids which thus leak into the suction side of the compressor tend to throttle or subtract from the charge of incoming gas and thus reduce volumetric efficiency.

As best shown in FIGS. 2 and 8, in accordance with the present invention, the compressor 10 is provided with means designated generally by the numeral 53 for demisting the refrigerant-lubricant mixture that passes without the compressor 10. These means for demisting 53 comprise a zone or compartment defining member 40 which is formed in a unitary structure generally aflixed in a plane transverse to the axis of the rotor 33. The member 40 divides the sections of the casing into a front chamber or zone A in communication with the outlets from the reed valves and a rear chamber or zone B in communication with the exit port passage 93. The member 40 has an outer edge 40 of conforming but slightly smaller size than the inside size of the casing 11 at its point of afiixture. Thus, the outer edge 40' is of circular configuration. About the outer edge 40 is affixed a seal 27 of a flexible material such as rubber. The seal 27 extends to the interior surface of the housing 11 and there makes sealing contact. The member 40 has an outstanding annular extension 40a of general L-shape in cross-section positioned eccentrically to conform with a bearing housing extension 38 of the rear bearing plates 37. The extension 40a comprises an outstanding circularly curved wall 40b, centered about the shaft portion 42, and a planar portion 400 extending from the end of wall 40b and terminating in an inwardly curving lip 40d of a circular shape. The lip 40d is positioned about but spaced from the curved outer surface of the extension 38. The bearing plate 37 has an annular shaped bore 37:: formed therein about the extension 38 and opposite the portion 400 of the member 40. The member 40 is afiixed to the plate 37 about the periphery thereof by means of the bolts 36 which pass through conforming holes in the member 40. Positioned between the front facing portion 40c of the member 40 and the annular base 37a of the plate 37 is a demisting element 290 of a generally annular shape. The demisting element 200 has a generally rectangular cross-section with a planar forward facing surface 200a abutting against the interior surface of the base 37a and a rearward facing surface abutting against the frontward facing surface of portion 400 of the member 40.

During compressor operation a small pressure differential exists between chambers A and B shown in FIG. 2. This pressure differential forces the mixture of superheated refrigerant and lubricant suspended in particle form in chamber A to flow through channels 90 into chamber C surrounding the demister element 200, through the demister element 200 and exit around the rear bearing plate hub 38. The demister element 200 consists of a suitably porous material which has the property of causing fine particles of lubricant dispersed in refrigerant to collect and exit in droplet form. The lubricant droplets are sufficiently heavy to fall out of the refrigerant stream and drop into the lubricant reservoir 190.

One main advantage of reducing the percent of lubricant circulated around the air conditioning system is that under certain operating conditions the lubricant tends to become trapped in the evaporator and condenser which reduces the heat transfer efficiency of those units. The demister apparatus 53 thus serves to improve overall refrigeration system efliciency because of the ability of the compressor to retain lubricant as well as to improve the efficiency of the compressor.

Since the gas pressure inside of the rotor 33 is less than the discharge pressure inside of the casing 11, lubricant flows up the lubricant pick-up tube 98 and passes through the wall 109 to lubricate the needle bearings 39. Upon passing through the needle bearing assembly 39, part of the lubricant enters the rear annular clearance between the rear end plate 37 and the adjoining side face of the rotor 33, and part of the lubricant travels through the splines 52, 56 and across the inner ends of the vanes 61 to lubricate the vanes and the ball bearing assembly 46 and the rotary seal 48. The remaining lubricant passes through the front annular clearance between the front bearing plate 13 and the adjoining side face of the rotor t? 33. Lubricant in the two clearance annuluscs serves the dual purpose of lubrication and retarding the rate of refrigerant flow from the discharge to the suction side of the compressor. Upon entering the pumping chamber, the shoes 64 are lubricated.

It is contemplated to provide scavenging grooves on the suction side of the compressor one of which is most clearly shown in FIG. 5 of the drawings at 11 It will be noted that the scavenging groove has an end 117 spaced inwardly of the inlet recess 77 and the groove 1116 extends circumferentially towards the discharge side of the pump terminating in an outwardly directed leg identified at 118. Such a scavenging groove 116 is located in both the radial face of the front bearing plate 13 as well as the radial face of the rear bearing plate 37 and such grooves trap refrigerant and lubricant migrating towards the suction side of the compressor through the clearance spaces between the adjoining side faces of the bearing plates and the rotor. Fluids trapped by the scavenging grooves 116, 115 travel counterclockwise and are discharged through the discharge ends 118, 118 communieating with the working chamber 79 at a location such that the portions 118 are opened immediately after the suction kidney is closed, as shown in FIG. 3. The pressure in the scavenging grooves 116, therefore, fluctuates depending upon the position of the rotor 33 and the vane 61. Although flow reversal in the grooves 116, 116 can occur under some conditions for a fraction of the cycle, the net effect is for counterclockwise flow by preventing most of the gas and lubricant from leaking into the suction side of the compressor, the maximum charge of refrigerant can enter the suction side of the compressor and high volumetric efiiciency and reduced discharge temperatures result.

It may be noted that the shoes 64 are designed to minimize wear and torque required to move them since the planing action of the shoes causes the shoes to ride up on the lubricant, thereby providing a tendency for the shoes 54 to float. During continuous operation, therefore, the shoes 64 Will rarely touch the cylinder Walls 32.

Since the lubricant pickup 98 is swivelly mounted, gravity causes the tube 98 to extend into the lubricant pool in the casing 11 regardless of the plane or orientation in which the compressor is mounted. Thus, any given compressor can be used in many different system applications and it is not necessary to have a large inventory of assembled compressors for different types of installations.

Once the compressor is put into operation, the lubricant pickup tube 98 is rigidly held in place by the differential of pressure occurring between the pressure reservoir and the interior of the pump since the flange 108 is pressurebiased against the wall 166. In addition to holding the lubricant pickup tube 98 in place, the flange 108 serves as a seal to prevent gaseous refrigerant from leaking into the interior of the pump around the flange and through the clearance between the outside of the hub 106 and the opening 101 in the wall 100.

Although minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention:

1. A compressor comprising:

a casing cylinder having a bore formed therein,

front and rear bearing plates on opposite sides of said casing cylinder,

a rotor shaft journaled in said bearing plates and extending through said bore on an axis eccentrically offset relative to the bore axis,

a rotor on said shaft having a tangent seal contact with the bore wall and forming therewith a crescentshaped working chamber,

splined coupling means between said shaft and said rotor affording self-centering movement of said rotor between said bearing plates, said rotor having a plurality of circumferentially spaced peripheral vane slots formed therein,

a vane in each said slot,

pins extending through said shaft between oppositely disposed vanes and having coil springs around said pins and engaging said vanes to pressure-bias said vanes outwardly against the adjoining bore wall, said front bearing plate having an inlet valve and a discharge valve and being formed with an inlet kidneyshaped recess adjacent one side of said working chamber,

at least one of said bearing plates having formed therein a scavenging groove formed axially opposite said rotor and extending circumferentially on the inlet side of the compressor and spaced radially inwardly of said inlet recess, said scavenging groove having a discharge end extending radially outwardly into the working chamber to minimize gas and lubricant leakage into the suction side of the compressor,

outlet means for conducting pressurized fluid from the working chamber to a point of utilization, said outlet means comprising a boss formed on said casing cylinder adjacent said tangent seal contact and forming a flat valve seating surface, and said casing cylinder having a double row of parallel circumferentially spaced openings forming ports extending outwardly from the outlet side of said working chamber through said valve seating surface,

a valve means on said boss comprising plural resilient reeds corresponding in number to said openings and engaging said valve seating surface to regulate said poi ts, said valve reeds opening in unison and closing said ports in pairs, said boss having a recess spaced adjacent each row of openings to vent the underside of said reeds,

a casing surrounding said casing cylinder and forming a pressure reservoir for receiving the fluid pressurized in said pump,

means for demisting comprising a demisting element for causing said lubricant to form in larger sized droplets than normal, said element being positioned in said casing in said reservoir and defining therewith a lubricant reservoir, and said means for demisting including a generally planar circular casing dividing member for affixing to said rear bearing plate and defining with said plate an annulus-receiving cavity, said member dividing said easing into front and rear chambers being in communication with said reed valves and said rear chamber being in communication with said compressor output means and forming said lubricant reservoir, said demisting element being annular in shape and postioned between said member and said rear bearing plate in said annulusreceiving cavity so that said fluid in flowing from said reed valves to said outlet passes through said demisting element,

a tube carried by said rear bearing plate for swivel movement and depending gravitationally towards the bottom of the lubricant reservoir for conducting liquid lubricant to said rotor shaft, said tube being swivelly adjustable in response to the orientation of the compressor, said front bearing plate having plural mounting pads for effecting left, right and vertical mounting of said compressor, said swivel tube having a flange overlying said rear bearing plate to form a pressure loaded seal with the adjoining surface during operation of the compressor,

a second boss formed on said casing cylinder providing a second series of valve controlled discharge ports extending towards the inlet side of the compressor for low pressure discharge operating conditions, and further characterized by the size of each said opening being smaller than the circumferential width of a vane to prevent by-passing across the ports, and

a shoe pivotally carried on the end of each said vane and each shoe having a leading end longer than the trailing end thereof to develop a planing action relative to the lubricant and the adjoining bore wall.

2. A compressor comprising:

inner and outer casings forming a pumping chamber in said inner casing and a pressure reservoir between said casings,

inlet means communicating with said pumping chamber,

outlet means between said pumping chamber and said pressure reservoir,

means for demisting comprising a demisting element for causing said lubricant to form in larger sized droplets than normal, said element being positioned in said casing in said reservoir, said means for demisting being further characterized by the inclusion of an annular member having an outer periphery generally conforming to the interior shape of said casing for dividing said reservoir into a first and second zone, said demisting element being affixed in relation to said annular member so as to cause fluid flowing from said first zone to said second zone to pass therethrough,

discharge means extending outwardly from said pressure reservoir for connection to a point of utilization,

a rotary fluid displacement means journaled for rotation in said inner casing.

3. The compressor for a refrigerant system comprising:

a casing cylinder having a bore formed therein,

front and rear bearing plates on opposite sides of said casing cylinder, said rear bearing plate having a rotor shaft receiving boss outstanding therefrom,

a rotor shaft journaled in said bearing plates and extending through said bore on an axis eccentrically offset relative to the bore axis,

a rotor on said shaft having a tangent seal contact with the bore wall and forming therewith a crescentshaped working chamber,

outlet means for conducting pressurized fluid from the working chamber,

a casing surrounding said casing cylinder and forming a pressure reservoir for receiving the fiuid pressurized in said pump and having an exit port formed therein,

means for demisting comprising a compartment defining member which is formed in a unitary structure generally aflixed in a plane transverse to the axis of the rotor and which divide the pressure reservoir into a front chamber and a rear chamber in which the front chamber is in communication with the outlet means from said working chamber and the rear chamber is in communication with said exit port, and the member furthermore has an edge conforming in configuration to the interior of said casing about the outer edge of which is aflixed a seal constructed of a flexible material which extends to the interior surface of the casing and makes contact therewith, the member having an outstanding annular extension of generally L-shape in cross-section positioned to conform with the rear bearing plate shaft receiving boss, the extension comprising an outstanding circular curved wall centered about the shaft boss and a planar portion extending from the wall and terminating in an inwardly curving lip of circular shape which is positioned about but spaced from the outer surface of said boss; and

an annular shaped demisting element positioned in said annular extension of said member and extending between said rear bearing plate and said member so that fluid from said front chamber to said rear chamher must pass therethrough, said element being generally porous and having the property of causing droplets of lubricant to form in larger droplets than otherwise.

4. The improvement as claimed in claim 3 in which said edge of said member is circular in shape, and said seal is of rubber.

5. The compressor as claimed in claim 2 further including a tube swivelly mounted in one end of said inner casing and depending into said pressure reservoir and forming a passage for conducting pressurized liquid lubricant from the lowermost portion of the reservoir into the inner casing for lubricating the fluid displacement means.

References Cited UNITED STATES PATENTS Schutten 222-321 McCormack 230-152 Klessig et al. 103-220 Wellborn et a1. 230-152 X Boettcher 230-207 Rhode 103-220 Galin 230-152 X Harlin 230-207 Huyser et al. 230-152 FRED C. MA'ITERN, 111., Primary Examiner.

15 W. J. KRAUSS, Assistant Examiner. 

1. A COMPRESSOR COMPRISING: A CASING CYLINDER HAVING A BORE FORMED THEREIN, FRONT AND REAR BEARING PLATES ON OPPOSITE SIDES OF SAID CASING CYLINDER, A ROTOR SHAFT JOURNALED IN SAID BEARING PLATES AND EXTENDING THROUGH SAID BORE ON AN AXIS ECCENTRICALLY OFFSET RELATIVE TO THE BORE AXIS, A ROTOR ON SAID SHAFT HAVING A TANGENT SEAL CONTACT WITH THE BORE WALL AND FORMING THEREWITH A CRESCENTSHAPED WORKING CHAMBER, SPLINED COUPLING MEANS BETWEEN SAID SHAFT AND SAID ROTOR AFFORDING SELF-CENTERING MOVEMENT OF SAID ROTOR BETWEEN SAID BEARING PLATES, SAID ROTOR HAVING A PLURALITY OF CIRCUMFERENTIALLY SPACED PERIPHERAL VANE SLOTS FORMED THEREIN, A VANE IN EACH SAID SLOT, PINS EXTENDING THROUGH SAID SHAFT BETWEEN OPPOSITELY DISPOSED VANES AND HAVING COIL SPRINGS AROUND SAID PINS AND ENGAGING SAID VANES TO PRESSURE-BIAS SAID VANES OUTWARDLY AGAINST THE ADJOINING BORE WALL, SAID FRONT BEARING PLATE HAVING AN INLET VALVE AND A DISCHARGE VALVE AND BEING FORMED WITH AN INLET KIDNEYSHAPED RECESS ADJACENT ONE SIDE OF SAID WORKING CHAMBER, AT LEAST ONE OF SAID BEARING PLATES HAVING FORMED THEREIN A SCAVENGING GROOVE FORMED AXIALLY OPPOSITE SAID ROTOR AND EXTENDING CIRCUMFERENTIALLY ON THE INLET SIDE OF THE COMPRESSOR AND SPACED RADIALLY INWARDLY OF SAID INLET RECESS, SAID SCAVENING GREOOVE HAVING A DISCHARGE END EXTENDING RADIALLY OUTWARDLY INTO THE WORKING CHAMBER TO MINIMIZE GAS AND LUBRICANT LEAKAGE INTO THE SUCTION SIDE OF THE COMPRESSOR, OUTLET MEANS FOR CONDUCTING PRESSURIZED FLUID FROM THE WORKING CHAMBER TO A POINT OF UTILIZATION, SAID OUTLET MEANS COMPRISING A BOSS FORMED ON SAID CASING CYLINDER ADJACENT SAID TANGENT SEAL CONTACT AND FORMING A FLAT VALVE SEATING SURFACE, AND SAID CASING CYLINDER HAVING A DOUBLE ROW OF PARALLEL CIRCUMFERENTIALLY SPACED OPENINGS FORMING PORTS EXTENDING OUTWARDLY FROM THE OUTLET SIDE OF SAID WORKING CHAMBER THROUGH SAID VALVE SEATING SURFACE, 